generic: add a new test for racing AIO COW writes

This can be used to trigger an assert in the current XFS code
because it can't handle the case where there are COW extents on a
file, but none at or below the range converted by the AIO completion
handler.

Note that it doesn't trigger the assert 100% but fairly reliably.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

.gitignore

@@ -142,6 +142,7 @@
 /src/writemod
 /src/writev_on_pagefault
 /src/xfsctl
+/src/aio-dio-regress/aio-dio-cow-race
 /src/aio-dio-regress/aio-dio-cycle-write
 /src/aio-dio-regress/aio-dio-eof-race
 /src/aio-dio-regress/aio-dio-extend-stat

src/aio-dio-regress/aio-dio-cow-race.c

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) Christoph Hellwig.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <libgen.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <sys/ioctl.h>
+#include <linux/fs.h>
+
+#include <libaio.h>
+
+#ifndef FICLONE
+#define FICLONE		_IOW(0x94, 9, int)
+#endif
+
+#define IO_PATTERN	0xab
+
+int main(int argc, char *argv[])
+{
+	struct io_context *ctx = NULL;
+	struct io_event evs[4];
+	struct iocb iocb1, iocb2, iocb3, iocb4;
+	struct iocb *iocbs[] = { &iocb1, &iocb2, &iocb3, &iocb4 };
+	void *buf;
+	int fd, clone, err = 0;
+	unsigned long buf_size = getpagesize() * 2;
+	char *filename, *clonename;
+
+	if (argc != 3) {
+		fprintf(stderr, "usage: %s filename clonename\n", argv[0]);
+		exit(1);
+	}
+
+	err = posix_memalign(&buf, getpagesize(), buf_size);
+	if (err) {
+		fprintf(stderr, "error %s during %s\n",
+			strerror(err), "posix_memalign");
+		return 1;
+	}
+	memset(buf, IO_PATTERN, buf_size);
+
+	filename = argv[1];
+	fd = open(filename, O_DIRECT | O_CREAT | O_TRUNC | O_RDWR, 0600);
+	if (fd == -1) {
+		perror("open");
+		return 1;
+	}
+
+	if (write(fd, buf, buf_size) != buf_size) {
+		perror("write");
+		return 1;
+	}
+
+	clonename = argv[2];
+	clone = open(clonename, O_DIRECT | O_CREAT | O_TRUNC | O_RDWR, 0600);
+	if (clone == -1) {
+		perror("open clone");
+		return 1;
+	}
+
+	if (ioctl(clone, FICLONE, fd)) {
+		perror("FICLONE");
+		return 1;
+	}
+
+	err = io_setup(4, &ctx);
+	if (err) {
+		fprintf(stderr, "io_setup error: %s\n", strerror(err));
+		return 1;
+	}
+
+	/*
+	 * Test overlapping aio writes, where an earlier one clears the whole
+	 * range of a later aio, thus leaving nothing to do for the I/O
+	 * completion to do.  To make things harder also make sure there is
+	 * other outstanding COW I/O.
+	 */
+	io_prep_pwrite(&iocb1, fd, buf, buf_size, 0);
+	io_prep_pwrite(&iocb2, fd, buf, buf_size / 2, 0);
+	io_prep_pwrite(&iocb3, fd, buf, buf_size / 2, buf_size);
+	io_prep_pwrite(&iocb4, fd, buf, buf_size, 0);
+
+	err = io_submit(ctx, 4, iocbs);
+	if (err != 4) {
+		fprintf(stderr, "io_submit error: %s\n", strerror(err));
+		return 1;
+	}
+
+	err = io_getevents(ctx, 4, 4, evs, NULL);
+	if (err != 4) {
+		fprintf(stderr, "io_getevents error: %s\n", strerror(err));
+		return 1;
+	}
+
+	return 0;
+}

tests/generic/463

@@ -0,0 +1,59 @@
+#! /bin/bash
+# FS QA Test 463
+#
+# Test racy COW AIO write completions.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2017 Christoph Hellwig.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+	rm -f $TEST_DIR/file $TEST_DIR/clone
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/reflink
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+_supported_fs generic
+_supported_os Linux
+
+_require_test
+_require_test_reflink
+_require_aiodio aio-dio-cow-race
+
+$AIO_TEST $TEST_DIR/file $TEST_DIR/clone
+
+echo "Silence is golden"
+status=0
+exit

tests/generic/463.out

@@ -0,0 +1,2 @@
+QA output created by 463
+Silence is golden

tests/generic/group

@@ -465,3 +465,4 @@
 460 auto quick rw
 461 auto shutdown stress
 462 auto quick dax
+463 auto quick clone dangerous